Is Pre-Eruptive Null Point Reconnection Required for Triggering Eruptions?

We study the magnetic field evolution and topology of the active region NOAA 10486 before the 3B/X1.2 flare of October 26, 2003, using observational data from the French–Italian THEMIS telescope, the Michelson Doppler Imager (MDI) onboard Solar and Heliospheric Observatory (SOHO), the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observation Station (HSOS), and the Transition Region and Coronal Explorer (TRACE). Three dimensional (3D) extrapolation of photospheric magnetic field, assuming a potential field configuration, reveals the existence of two magnetic null points in the corona above the active region. We look at their role in the triggering of the main flare, by using the bright patches observed in TRACE 1600 Å images as tracers at the solar surface of energy release associated with magnetic reconnection at the null points. All the bright patches observed before the flare correspond to the low-altitude null point. They have no direct relationship with the X1.2 flare because the related separatrix is located far from the eruptive site. No bright patch corresponds to the high-altitude null point before the flare. We conclude that eruptions can be triggered without pre-eruptive coronal null point reconnection, and the presence of null points is not a sufficient condition for the occurrence of flares. We propose that this eruptive flare results from the loss of equilibrium due to persistent flux emergence, continuous photospheric motion and strong shear along the magnetic neutral line. The opening of the coronal field lines above the active region should be a byproduct of the large 3B/X1.2 flare rather than its trigger.     

Flux Ropes Embedded In A Radial Magnetic Field: Analytic Solutions For The External Magnetic Field

Three sympathetic flares were observed with the Solar Magnetic Field Telescope (SMFT) at the Huairou Solar Observing Station of Beijing Astronomical Observatory on 29 August, and 1 September 1990. Each set of sympathetic flares had three ribbons. Two ribbons appeared in active region NOAA 6233 and one ribbon occurred in NOAA 6240 embedded in a single polarity area. Photospheric vector magnetograms were simultaneously obtained from both regions as well. We use a new numerical technique to reconstruct the chromospheric and coronal magnetic fields by making use of the observed vector magnetic fields in the photosphere as boundary conditions. Magnetic field loops linking both regions were identified from the reconstructed 3-D fields. The analysis of chromospheric filtergrams and reconstructed 3-D magnetic fields indicates that interaction between a sheared lower loop in the active region NOAA 6233 and a higher loop linking the two regions resulted in sympathetic flares. The analysis of the time delay between flare ribbons in NOAA 6233 and 6240 indicates that heat conduction along the higher loop from the primary energy release site is responsible for the sympathetic flaring in NOAA 6240. The events reported in this paper represent only one alternative as the cause of sympathetic flaring in which energy transport along coronal interconnecting loops plays the major role, and no in-situ energy release is required.     

Magnetic Field Strengths and Structures from Radio Observations of Solar Active Regions

Radio observations of some active regions (ARs) obtained with the Nobeyama radioheliograph at λ=1.76cm are used for estimating the magnetic field strength in the upper chromosphere, based on thermal bremsstrahlung. The results are compared with the magnetic field strength in the photosphere from observations with the Solar Magnetic Field Telescope (SMFT) at Huairou Solar Observing Station of Beijing Astronomical Observatory. The difference in the magnetic field strength between the two layers seems reasonable. The solar radio maps of active regions obtained with the Nobeyama radioheliograph, both in total intensity (I-map) and in circular polarizations (V-map), are compared with the optical magnetograms obtained with the SMFT. The comparison between the radio map in circular polarization and the longitudinal photospheric magnetogram of a plage region suggest that the radio map in circular polarization is a kind of magnetogram of the upper chromosphere. The comparison of the radio map in total intensity with the photospheric vector magnetogram of an AR shows that the radio map in total intensity gives indications of magnetic loops in the corona, thus we have a method of defining the coronal magnetic structure from the radio I-maps at λ=1.76 cm. Analysing the I-maps, we identified three components: (a) a compact bright source; (b) a narrow elongated structure connecting two main magnetic islands of opposite polarities (observed in both the optical and radio magnetograms); (c) a wide, diffuse, weak component that corresponds to a wide structure in the solar active region which shows in most cases an S or a reversed S contour, which is probably due to the differential rotation of the Sun. The last two components suggest coronal loops on different spatial scales above the neutral line of the longitudinal photospheric magnetic field.     

ANALYSES OF VECTOR MAGNETOGRAMS IN FLARE-PRODUCTIVE ACTIVE REGIONS

This paper reviews studies of the relationship between the evolution of vector magnetic fields and the occurrence of major solar flares. Most of the data were obtained by the video magnetograph systems at Big Bear Solar Observatory (BBSO) and Huairou Solar Observatory (HSO). Due to the favorable weather and seeing conditions at both stations, high-resolution vector magnetograph sequences of many active regions that produced major flares during last solar maximum (1989–1993) have been recorded. We have analyzed several sequences of magnetograms to study the evolution of vector magnetic fields of flare productive active regions. The studies have focused on the following three aspects: (1) processes which build up magnetic shear in active regions; (2) the pre-flare magnetic structure of active regions; and (3) changes of magnetic shear immediately preceding and following major flares. We obtained the following results based on above studies: (1) Emerging flux regions (EFRs) play very important roles in the production of complicated photospheric flow patterns, magnetic shear and flares. (2) Although the majority of flares prefer to occur in magnetically sheared regions, many flares occurred in regions without strong photospheric magnetic shear. (3) We found that photospheric magnetic shear increased after all the 6 X-class flares studied by us. We want to emphasize that this discovery is not contradictory to the energy conservation principle, because a flare is a three-dimensional process, and the photosphere only provides a two-dimensional boundary condition. This argument is supported by the fact that if two initial ribbons of a flare are widely separated (which may correspond to a higher-altitude flare), the correlation of the flare with strong magnetic shear is weak; if the two ribbons of a flare are close (which may correspond to a lower-altitude flare), its correlation with the strong shear is strong. (4) We have analyzed 18 additional M-class flares observed by HSO in 1989 and 1990. No detectable shear change was found for all the cases. It is likely that only the most energetic flares can affect the photospheric magnetic topology.     

A Spatio-temporal Description of the Abrupt Changes in the Photospheric Magnetic and Lorentz-Force Vectors During the 15 February 2011 X2.2 Flare

The active region NOAA 11158 produced the first X-class flare of Solar Cycle 24, an X2.2 flare at 01:44 UT on 15 February 2011. The Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO) satellite produces 12-minute, 0.5′′ pixel^?1 vector magnetograms. Here we analyze a series of these data covering a 12-hour interval centered at the time of this flare. We describe the spatial distributions of the photospheric magnetic changes associated with the flare, including the abrupt changes in the field vector, vertical electric current and Lorentz-force vector acting on the solar interior. We also describe these parameters’ temporal evolution. The abrupt magnetic changes were concentrated near the neutral line and in two neighboring sunspots. Near the neutral line, the field vectors became stronger and more horizontal during the flare and the shear increased. This was due to an increase in strength of the horizontal field components near the neutral line, most significant in the horizontal component parallel to the neutral line but the perpendicular component also increased in strength. The vertical component did not show a significant, permanent overall change at the neutral line. The increase in field strength at the neutral line was accompanied by a compensating decrease in field strength in the surrounding volume. In the two sunspots near the neutral line the integrated azimuthal field abruptly decreased during the flare but this change was permanent in only one of the spots. There was a large, abrupt, downward vertical Lorentz-force change acting on the solar interior during the flare, consistent with results of past analyses and recent theoretical work. The horizontal Lorentz force acted in opposite directions along each side of neutral line, with the two sunspots at each end subject to abrupt torsional forces relaxing their magnetic twist. These shearing forces were consistent with a contraction of field and decrease of shear near the neutral line, whereas the field itself became more sheared as a result of the field collapsing towards the neutral line from the surrounding volume. The Lorentz forces acting on the atmospheric volume above the photosphere were equal and opposite.     

基于支持向量机的太阳磁场活动区极性反转线位置的探测

太阳磁场的极性反转线(Polarity Inversion Line, PIL)是研究太阳活动、分析太阳磁场结构演变和预测太阳耀斑最重要的日面特征之一.磁场极性反转的位置是太阳耀斑和暗条可能出现的位置."先进天基太阳天文台(ASO-S)"是中国首颗空间太阳专用观测卫星,其搭载的"全日面矢量磁像仪(Full-Disk Vector Magnetograph, FMG)"主要任务是探测高空间、高时间分辨率的全日面矢量磁场.为了提高观测数据使用效率、快速监测太阳活动水平、提高太阳耀斑与日冕物质抛射的预报水平以及更好地服务于FMG数据处理与分析系统,采用了图像自动识别与处理技术,更加精确有效地检测极性反转线.从支持向量机(Support Vector Machine, SVM)的模型出发,将极性反转线位置的探测问题转化为一个模式识别中的二分类问题,提出了一种基于支持向量机的极性反转线检测算法,自动探测与识别太阳动力学天文台(Solar Dynamics Observatory, SDO)日震和磁成像仪(Helioseismic and Magnetic Imager, HMI)磁图的极性反转线位置.与现有算法的对比结果表明,此算法可以精确直观地检测太阳活动区的极性反转线.     

Irreversible rapid changes of magnetic field associated with the 2012 October 23 circular near-limb X1.8 Flare

It has been found that photospheric magnetic fields can change in accordance with restructuring of the three-dimensional magnetic field following solar eruptions.Previous studies mainly use vector magnetic field data taken for events near the disk center.In this paper,we analyze the magnetic field evolution associated with the 2012 October 23 X1.8 flare in NOAA AR 11598 that is close to the solar limb,using both the 45 s cadence line-of-sight and 12 min cadence vector magnetograms from the Helioseismic and Magnetic Imager on board Solar Dynamics Observatory.This flare is classified as a circular-ribbon flare with spine-fan type magnetic topology containing a null point.In the line-of-sight magnetograms,there are two apparent polarity inversion lines(PILs).The PIL closer to the limb is affected more by the projection effect.Between these two PILs there lie positive polarity magnetic fields,which are surrounded by negative polarity fields outside the PILs.We find that after the flare,both the apparent limb-ward and disk-ward negative fluxes decrease,while the positive flux in-between increases.We also find that the horizontal magnetic fields have a significant increase along the disk-ward PIL,but in the surrounding area,they decrease.Synthesizing the observed field changes,we conclude that the magnetic fields collapse toward the surface above the disk-ward PIL as depicted in the coronal implosion scenario,while the peripheral field turns to a more vertical configuration after the flare.We also suggest that this event is an asymmetric circular-ribbon flare:a flux rope is likely present above the disk-ward PIL.Its eruption causes instability of the entire fan-spine structure and the implosion near that PIL.     

The Evolution of Quasi-Separatrix Layer in Two Solar Eruptive Events

Quasi-separatrix layer, also called as QSL, is a region where magnetic connectivity changes drastically, and mostly well coincides with the location of flare ribbons in observations. The research on the relations of this topological structure with the 3-dimensional magnetic reconnection, and solar flares has attracted more and more attention. In this paper, using the theory of QSL we investigate a C5.7 classical two-ribbon solar flare (event 1) which occurred at AR11384 on 2011 December 26, and an M6.5 solar flare (event 2) which occurred at AR12371 on 2015 June 22, respectively. Combining the multi-wavelength data of AIA (Atmospheric Imaging Assembly) and vector magnetogrames of HMI (Helioseismic and Magnetic Imager) onboard SDO (Solar Dynamics Observatory), we extrapolate the coronal magnetic field using the PF (Potential Field) and NLFFF (Nonlinear Force Free Field) models, and calculate the evolution of the AR (Active Region) magnetic free energy. Then, we calculate the logarithmic distribution of Q-factors (magnetic squashing factor) at different heights above the solar photosphere with the results of the PF and NLFFF extrapolations, in order to determine the location of QSL. Afterward, we investigate the evolutionary relation between the QSLs at different heights above the solar photosphere and the flare ribbons observed at the corresponding heights. Finally, we study the multi-wavelength evolution features of the 2 flare events, and obtain by calculation the mean slip velocities of magnetic lines in the event 2 at 304 Å and 335 Å to be 4.6 km s^-1 and 6.3 km s^-1, respectively. We find that the calculated location of QSL in the chromosphere and corona is in good agreement with the location of flare ribbons at the same height, and the QSLs at different heights have almost the same evolutionary behavior in time as the flare ribbons of the corresponding heights, which highlights the role of QSL in the research of 3D magnetic reconnection and solar flare, and we suggest that the energy release in the flare of event 2 may be triggered by the magnetic reconnection at the place of QSL. We also suggest that the QSL is very important for us to study the essential relation between the 3D and 2D magnetic reconnections.     

On the periodicity of energy release in solar active regions

We investigate the periodic regimes of energy release on the Sun, namely, the recurrence of solar flares in active regions using the Solar Geophysical Data Journal on Hα flares from 1979 until 1981, which corresponds to the maximum of solar cycle 21. We obtained the following series of periods in the manifestation of flare activity bymeans of a correlation periodogram analysis, a self-similarity function, and a wavelet analysis: ～1, 2, 3 h as well as ～0.4, 1, 2, 5 days. We suggest a diffusive model for the quasi-periodic transfer of toroidal magnetic fields from under the photosphere to interpret the retrieved sequence of periods in the enhancement of flare activity. We estimated the typical spatial scales of the magnetic field variations in the solar convection zone: ～17 000 km.     

Reports on Test Observations with the Multi-Channel Solar Telescope

In this paper, we have made a report on the test observations with a Multi-Channel Solar Telescope (MCST), which consists of 60 cm Nine-Channel Solar Telescope (NCST), 35 cm Solar Magnetic Field Telescope (SMFT), 8 cm Full Disc Telescope (FDT), 10 cm Full Disc Magnetic Field Telescope (FDMFT) and 14 cm H telescope. These observations demonstrate that the MCST has the following advantages: (a) It can work at more than nine visible spectral lines simultaneously. In this way, different solar layers of the photosphere and chromosphere can be observed at the same time; (b) every channel of the NCST is entirely equivalent to a videomagnetograph, by means of which the vector magnetic fields and line-of-sight velocity fields can be measured; (c) real-time monochromatic images of the photosphere and chromosphere can be obtained with the FDT, FDMFT, and H Telescope; (d) high-temporal-resolution full-disk magnetic fields can be measured with the FDMFT; (e) spectral profiles over a large field of view can be scanned with the NCST.     

The Relationship Between Plasma Flow Doppler Velocities and Magnetic Field Parameters During the Emergence of Active Regions at the Solar Photospheric Level

A statistical study has been carried out of the relationship between plasma flow Doppler velocities and magnetic field parameters during the emergence of active regions at the solar photospheric level with data acquired by the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO). We have investigated 224 emerging active regions with different spatial scales and positions on the solar disc. The following relationships for the first hours of the emergence of active regions have been analysed: i) of peak negative Doppler velocities with the position of the emerging active regions on the solar disc; ii) of peak plasma upflow and downflow Doppler velocities with the magnetic flux growth rate and magnetic field strength for the active regions emerging near the solar disc centre (the vertical component of plasma flows); iii) of peak positive and negative Doppler velocities with the magnetic flux growth rate and magnetic field strength for the active regions emerging near the limb (the horizontal component of plasma flows); iv) of the magnetic flux growth rate with the density of emerging magnetic flux; v) of the Doppler velocities and magnetic field parameters for the first hours of the appearance of active regions with the total unsigned magnetic flux at the maximum of their development.     

Variations of magnetic fields and electric currents associated with a solar flare

The high-resolution vector magnetograms obtained with the solar telescope magnetograph of the Beijing Astronomical Observatory of the active region AR 4862 on 7 October, 1987, close before and after a solar flare, were used to calculate the electric current densities in the region. Then the relations between the flare and the magnetic fields as well as the electric currents were studied. The results are: (i) the transverse magnetic fields, and hence the longitudinal electric currents in the region before and after the flare, are evidently different, while the longitudinal magnetic fields remain unchanged; (ii) this confirms the result obtained previously that the flare kernels coincide with the peaks of longitudinal electric density in active regions; (iii) the close relation between the flare kernels and the electric currents indicates that the variations of the transverse magnetic fields and the longitudinal electric currents arise not from the general global evolution of the active region, but from the flare. These results tend to the conclusion that the triggering of a solar flare might be related with the plasma instability caused by the surplus longitudinal electric currents at some local regions in the solar atmosphere.     

Vertical current and a 3B/X12 flare in a highly sheared active region (NOAA 6659) on June 9, 1991

NOAA active region 6659, during its June 1991 transit across the solar disk, showed highly sheared vector magnetic field structures and produced numerous powerful flares, including five white-light flares. Photospheric vector magnetograms of this active region were obtained at the Huairou Solar Observing Station of the Beijing Astronomical Observatory. After the resolution of the 180° ambiguity of the transverse magnetic field and transformation of off-center vector magnetograms to the heliographic plane, we have determined the photospheric vertical current density and discussed the relationship with powerful flares. The following results were obtained: (a) The powerful 3B/X12 flare on June 9, 1991 was triggered by the interaction between the large-scale electric current system and magnetic flux of opposite polarity. (b) The kernels of the powerful Hβ flare (sites of the white-light flare) were close to the peaks of the vertical electric current density. (c) Some small-scale structures of the vertical current relative to the magnetic islands of opposite polarity have not been found. This probably implies that the electric current is not always parallel to the magnetic field in solar active regions.     

Short-Term Solar Flare Prediction Using a Sequential Supervised Learning Method

Solar flares are powered by the energy stored in magnetic fields, so evolutionary information of the magnetic field is important for short-term prediction of solar flares. However, the existing solar flare prediction models only use the current information of the active region. A sequential supervised learning method is introduced to add the evolutionary information of the active region into a prediction model. The maximum horizontal gradient, the length of the neutral line, and the number of singular points extracted from SOHO/MDI longitudinal magnetograms are used in the model to describe the nonpotentiality and complexity of the photospheric magnetic field. The evolutionary characteristics of the predictors are analyzed by using autocorrelation functions and mutual information functions. The analysis results indicate that a flare is influenced by the 3-day photospheric magnetic field information before flare eruption. A sliding-window method is used to add evolutionary information of the predictors into machine learning algorithms, then C4.5 decision tree and learning vector quantization are employed to predict the flare level within 48 hours. Experimental results indicate that the performance of the short-term solar flare prediction model within the sequential supervised learning framework is significantly improved.     

The non-uniform pattern in full-disc vector magnetograms and its correction

The Solar Magnetism and Activity Telescope (SMAT) has been operational at Huairou Solar Observing Station since the end of 2005. Its scientific projects are the observational study of full-disc vector magnetic field and Hα chromospheric activities. In this paper, the Fourier low-frequency passing filter and the large-scale polynomials fit methods have been employed to analyse and remove the non-uniform pattern (NUP) in the full-disc Stokes V image. These methods are useful to effectively improve the quality of SMAT's data. The following main results have been obtained. (1) An intrinsic large-scale spatial distribution of NUP appears in SMAT's full-disc Stokes V image and its average amplitude accounts for 2 per cent of sunspots' field of kG. (2) NUP is testified as instrumental polarization through data reduction and observational explanation (passband shift). There are pseudo-passband shift in the wide field of view of SMAT due to NUP, and the maximum shifting value from the solar disc centre to the solar disc limb is 0.12 Å. (3) As an example, after removing SMAT's NUP in the Stokes V image, the correlation coefficients of the magnetograms become 78 per cent between SMAT and MDI (Michelson Doppler Imager project) on the SOHO ( Solar and Heliospheric Observatory ) satellite, and 92 per cent between SMAT and the SMFT (Solar Magnetic Field Telescope) at Huairou.     

The Evolution of Sunspot Magnetic Fields Associated with a Solar Flare

Solar flares occur due to the sudden release of energy stored in active-region magnetic fields. To date, the precursors to flaring are still not fully understood, although there is evidence that flaring is related to changes in the topology or complexity of an active-region’s magnetic field. Here, the evolution of the magnetic field in active region NOAA 10953 was examined using Hinode/SOT-SP data over a period of 12 hours leading up to and after a GOES B1.0 flare. A number of magnetic-field properties and low-order aspects of magnetic-field topology were extracted from two flux regions that exhibited increased Ca ii H emission during the flare. Pre-flare increases in vertical field strength, vertical current density, and inclination angle of ≈ 8° toward the vertical were observed in flux elements surrounding the primary sunspot. The vertical field strength and current density subsequently decreased in the post-flare state, with the inclination becoming more horizontal by ≈ 7°. This behavior of the field vector may provide a physical basis for future flare-forecasting efforts.     

Turbulence In The Solar Atmosphere: Manifestations And Diagnostics Via Solar Image Processing

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of solar magnetic fields. While these techniques advance our understanding of the physical system at work, it is unclear whether they can be used to predict solar eruptions, thus obtaining a practical significance for space weather. We address part of this problem by focusing on solar active regions and by investigating the usefulness of scaling and multi-scaling image-processing techniques in solar flare prediction. Since solar flares exhibit spatial and temporal intermittency, we suggest that they are the products of instabilities subject to a critical threshold in a turbulent magnetic configuration. The identification of this threshold in scaling and multi-scaling spectra would then contribute meaningfully to the prediction of solar flares. We find that the fractal dimension of solar magnetic fields and their multi-fractal spectrum of generalized correlation dimensions do not have significant predictive ability. The respective multi-fractal structure functions and their inertial-range scaling exponents, however, probably provide some statistical distinguishing features between flaring and non-flaring active regions. More importantly, the temporal evolution of the above scaling exponents in flaring active regions probably shows a distinct behavior starting a few hours prior to a flare and therefore this temporal behavior may be practically useful in flare prediction. The results of this study need to be validated by more comprehensive works over a large number of solar active regions. Sufficient statistics may also establish critical thresholds in the values of the multi-fractal structure functions and/or their scaling exponents above which a flare may be predicted with a high level of confidence. Based on the author's contributed talk “Manifestations and Diagnostics of Turbulence in the Solar Atmosphere”, presented at the Solar Image Processing Workshop II, Annapolis, Maryland, USA, 3–5 November 2004.     

Magnetic Fields and Solar Activities

We discuss the study of solar magnetic fields based on the photospheric vector magnetograms of solar active regions which were obtained at Huairou Solar Observing Station near Beijing in the period of 22nd and 23th solar cycles. The measurements of the chromospheric magnetic field and the spatial configuration of the field at the lower solar atmosphere inferred by the distribution of the solar photospheric and chromospheric magnetic field. After the analysis on the formation process of delta configuration in some super active regions based on the photospheric vector magnetogram observations, some results are obtained: (1) The analysis of magnetic writhe of whole active regions cannot be limited in the strong field of sunspots, because the contribution of the fraction of decayed magnetic field is non-negligible. (2) The magnetic model of kink magnetic ropes, proposed to be generated in the subatmosphere, is not consistent with the evolution of large-scale twisted photospheric transverse magnetic field and the relationship with magnetic shear in some delta active regions completely. (3) The proposition is that the large-scale delta active regions are formed from contribution by highly sheared non-potential magnetic flux bundles generated in the subatmosphere. We present some results of a study of the magnetic helicity. We also compare these results with other data sets obtained by magnetographs (or Stokes polarimeters) at different observatories, and analyze the basic chirality of the magnetic field in the solar atmosphere.     

A Measure of Magnetic Field Discontinuity

In this paper we introduce a measure of magnetic field discontinuity, MAD, defined as Maximum Angular Difference between two adjacent magnetic field vectors. To examine the characteristics of the MAD, we have considered several active region models having a quadrupolar field configuration and computed MADs over these active regions by approximating the 3-D magnetic fields as an ensemble of charge potential fields or linear force-free fields. The computed MAD fields are studied in comparison with other flare activity indicators such as separators. It is found that (1) the region of high level MAD corresponds well with the separator, or practically the intersection of the separator with the plane of measurement, (2) it singles out local discontinuities of magnetic fields, and (3) the MAD can also be a measure of the evolutionary status of an active region.An observational test has been made for 2-D MADs, using the Yohkoh SXT observation of a flare in AR 6919 and the vector magnetogram taken at the Mees Solar Observatory during this flare activity. The high level contours of 2-D MAD are found to trace well the observed soft X-ray bright points, which indicates that the MAD could serve as a good flare activity indicator.     

Predictions of Energy and Helicity in Four Major Eruptive Solar Flares

In order to better understand the solar genesis of interplanetary magnetic clouds (MCs), we model the magnetic and topological properties of four large eruptive solar flares and relate them to observations. We use the three-dimensional Minimum Current Corona model (Longcope, 1996, Solar Phys. 169, 91) and observations of pre-flare photospheric magnetic field and flare ribbons to derive values of reconnected magnetic flux, flare energy, flux rope helicity, and orientation of the flux-rope poloidal field. We compare model predictions of those quantities to flare and MC observations, and within the estimated uncertainties of the methods used find the following: The predicted model reconnection fluxes are equal to or lower than the reconnection fluxes inferred from the observed ribbon motions. Both observed and model reconnection fluxes match the MC poloidal fluxes. The predicted flux-rope helicities match the MC helicities. The predicted free energies lie between the observed energies and the estimated total flare luminosities. The direction of the leading edge of the MC’s poloidal field is aligned with the poloidal field of the flux rope in the AR rather than the global dipole field. These findings compel us to believe that magnetic clouds associated with these four solar flares are formed by low-corona magnetic reconnection during the eruption, rather than eruption of pre-existing structures in the corona or formation in the upper corona with participation of the global magnetic field. We also note that since all four flares occurred in active regions without significant pre-flare flux emergence and cancelation, the energy and helicity that we find are stored by shearing and rotating motions, which are sufficient to account for the observed radiative flare energy and MC helicity.